Comparison of the Chernobyl and Fukushima nuclear accidents: a review of the environmental impacts.

. On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 (133Xe) and the aerosol-bound caesium-137 (137Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 15.3 (uncertainty range 12.2–18.3) EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1–3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated 133Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h) into 133Xe. There is strong evidence that the 133Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For 137Cs, the inversion results give a total emission of 36.6 (20.1–53.1) PBq, or about 43% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14–15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude at the time when spraying of water on the spent-fuel pool of unit 4 started. This indicates that emissions may not have originated only from the damaged reactor cores, but also from the spent-fuel pool of unit 4. This would also confirm that the spraying was an effective countermeasure. We explore the main dispersion and deposition patterns of the radioactive cloud, both regionally for Japan as well as for the entire Northern Hemisphere. While at first sight it seemed fortunate that westerly winds prevailed most of the time during the accident, a different picture emerges from our detailed analysis. Exactly during and following the period of the strongest 137Cs emissions on 14 and 15 March as well as after another period with strong emissions on 19 March, the radioactive plume was advected over Eastern Honshu Island, where precipitation deposited a large fraction of 137Cs on land surfaces. Radioactive clouds reached North America on 15 March and Europe on 22 March. By middle of April, 133Xe was fairly uniformly distributed in the middle latitudes of the entire Northern Hemisphere and was for the first time also measured in the Southern Hemisphere (Darwin station, Australia). In general, simulated and observed concentrations of 133Xe and 137Cs both at Japanese as well as at remote sites were in good quantitative agreement. Altogether, we estimate that 6.4 PBq of 137Cs, or 18% of the total fallout until 20 April, were deposited over Japanese land areas, while most of the rest fell over the North Pacific Ocean. Only 0.7 PBq, or 1.9% of the total fallout were deposited on land areas other than Japan.

Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

Atmospheric Chemistry of Iodine Alfonso Saiz-Lopez,* John M. C. Plane,* Alex R. Baker, Lucy J. Carpenter, Roland von Glasow, Juan C. G omez Martín, Gordon McFiggans, and Russell W. Saunders Laboratory for Atmospheric and Climate Science (CIAC), CSIC, Toledo, Spain School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom School of Earth, Atmospheric & Environmental Sciences, University of Manchester, Manchester, M13 9PL, United Kingdom

Atmospheric Chemistry of Iodine

This review about the genus Laminaria sensu lato summarizes the extensive literature that has been published since the overview of the genus given by Kain in 1979. The recent proposal to divide the genus into the two genera Laminaria and Saccharina is acknowledged, but the published data are discussed under a 'sensu lato' concept, introduced here. This includes all species which have been considered to be 'Laminaria' before the division of the genus. In detail, after an introduction the review covers recent insights into phylogeny and taxonomy, and discusses morphotypes, ecotypes, population genetics and demography. It describes growth and photosynthetic performance of sporophytes with special paragraphs on the regulation of sporogenesis, regulation by endogenous rhythms, nutrient metabolism, storage products, and salinity tolerance. The biology of microstages is discussed separately. The ecology of these kelps is described with a focus on stress defence against abiotic and biotic factors and the role of Laminaria as habitat, its trophic interactions and its competition is discussed. Finally, recent developments in aquaculture are summarized. In conclusion to each section, as a perspective and guide to future research, we draw attention to the remaining gaps in the knowledge about the genus and kelps in general.

https://www.tandfonline.com/doi/pdf/10.1080/09670260701711376

The genus Laminaria sensu lato : recent insights and developments

The ecological interactions of brown algae are important as these macroalgae are common and often keystone members in many benthic marine communities. This review highlights their chemical interactions, particularly with potential herbivores, but also with fouling organisms, with potential pathogens, with each other as gametes, and with their microenvironments when they are spores. Phlorotannins, which are phenolic compounds unique to brown algae, have been studied heavily in many of these respects and are highlighted here. This includes recent controversy about their roles as defences against herbivory, as well as new understanding of their roles in primary cellular functions that may, in many instances, be more important than, and which at least have to be considered in concert with, any possible ecological functions. Brown algae have also been useful models for testing theories about the evolution of and ecological constraints on chemical defence. Furthermore, their microscopic motile gametes and spores have the ability to react to their chemical environments behaviourally.

Defensive and Sensory Chemical Ecology of Brown Algae

Production rates of bromoform (CHBr,), methylene bromide (CH,Br,), and methyl iodide (CH31) were measured in the laboratory for 11 species of marine macroalgae. Production rates of the volatile bromomethanes extrapolated to a global scale suggest that marine macroalgae produce 2 x 10" g Br yr-I (1 x lo9 mol Br yr I), 98% of which is bromoform. Laminarians (kelps) produce 61% of this organic Br. These calculations suggest that marine macroalgae are important in the biogeochemical cycling of Br. Seawater concentrations of CHBr,, CH,Br,, and CH,I were deter- mined from various southern California coastal locales. High concentrations were measured in seawater from the canopy and the bottom of a dense bed of Macrocystis as compared to other sites. Surface seawater concentrations of these halomethanes showed a strong cross-shore gradient with the highest concentration in the kelp canopy and the lowest at 5 km offshore. Seawater adjacent to decaying macroalgae on the bottom of a submarine canyon was not enriched in halomethanes relative to- surface water. Water exiting a productive estuary was enriched only with CH,Br,, although two algal species that are abundant there (U/vu and Enteromorpha) showed high laboratory

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1992.37.8.1652

Laboratory production of bromoform, methylene bromide, and methyl iodide by macroalgae and distribution in nearshore southern California waters

Phytoplankton (microalgae), seaweeds(macroalgae), higher plants and fungi producehalomethanes. Algae and fungi produce bothmethyl halides and polyhalomethanes, whereasplants are known to produce only methylhalides. Why these organisms producehalomethanes is a question frequently asked bychemists and biologists. This question impliesthat halomethanes have a function and have aselective value to the producing organism.Except for some fungi, the evolutionaryadvantage of producing halomethanes may notpresently exist. Polyhalomethanes areby-products of halogenation of certain organiccompounds by haloperoxidases in marine algaeand perhaps some fungi, and they may beindirectly produced in aquatic environments byalgal release of oxidized halogen species. Amain function of this enzyme is to rid the cellof harmful oxidants such as hydrogen peroxide.Monohalomethanes (methyl halides) are productsof methyltransferase activity. It has beenproposed that methyl halide production mayprovide a mechanism to regulate chloride levelsin halotolerant plants. The examination of halidecellular concentrations, halomethane productionrates, and enzyme characteristics raisesquestions about this possible function. Inalgae, plants and some fungi, methyl halidesmay be a result of the insertion of ubiquitoushalides into the active site of numerousmethyltransferases. Therefore, halomethanes maybe by-products or `accidents' of metabolism.

Phytogenesis of halomethanes: a product of selection or a metabolic accident?

An in situ incubation assay measuring the bromination and iodination of phenol red was developed to detect the release of reactive bromine and iodine (primarily hypobromous acid [HOBr] and hypoiodous acid [HOI], respectively) from a putative extracellular bromoperoxidase of marine diatoms. Six of 11 species showed significant release compared to controls. Polar species were particularly active, releasing 0.6–180 fmol HOBr cell21 h21 (0.04–1.8 mmol HOBr [mg total chlorophyll]21 h21; at the seawater bromide concentration, 840 mmol L21) and 1.9–271 fmol HOI cell21 h21 (0.02–2.7 mmol HOI [mg total chlorophyll]21 h21, at 100 mmol L21 iodide). Porosira glacialis consistently showed the highest rates of release. Several temperate diatoms, including Achnanthes cf longipes, known to have a bromide-sensitive peroxidase involved in stalk formation, and warmwater species also showed the ability to release reactive bromine and iodine. This release was influenced by light, temperature, bromide (and iodide) concentration, H2O2 concentration, and pH. The rate of HOBr release by polar diatoms was much greater than bromoform emissions measured by others from laboratory cultures and seaice algae in the field. This indicates that most of the HOBr released may react with dissolved organic matter (DOM) to form nonvolatile bromine organics. Some fraction of diatom-produced HOBr and HOI may also form volatile Br2 and I2, which could transfer to the polar troposphere. The reaction of diatom-released reactive bromine and iodine with seawater DOM may represent the major mechanism in the formation of oceanic polybromo- and polyiodo-methanes.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2009.54.3.0812

Release of reactive bromine and iodine from diatoms and its possible role in halogen transfer in polar and tropical oceans

Physiological factors affecting bromoform (CHBr3) production by Ulva lactuca were investigated using metabolic inhibitors and presumed substrates of bromoperoxidase (BrPO). The metabolic inhibitors were used at a verified physiologically active concentration. Bromoform production was nearly tripled in the light (376 ± 92 pg cm−2 h−1) compared to the dark (114 ± 70 pg cm−2 h−1), was inhibited in the light in the presence of the photosynthetic inhibitor DCMU, and was inhibited in the dark in the presence of mitochondrial respiratory inhibitor rotenone. Removal of H2O2 from seawater (treatment with catalase) decreased CHBr3 production in the light and dark. Addition of H2O2 to incubations at either 1.0 mM or 100 µM significantly decreased CHBr3 production in the light and inhibited photosynthesis. In the dark, CHBr3 production was decreased and respiration inhibited in the presence of 1 mM H2O2; CHBr3 production was enhanced and respiration was not affected in the presence of 100 µM H2O2. Removal of dissolved organic matter (DOM) from seawater decreased CHBr3 production, as did the addition of alternative BrPO substrates. These results suggest the presence of an extracellular and intracellular BrPO that protects the alga from both internally produced and externally present H2O2. The results show that H2O2 produced as a result of photosynthetic and respiratory electron transport, presumably by superoxide dismutase, is available to BrPO for bromination, and that the bromination of an unidentified metabolite (presumably Βߚketo acids) and a component of DOM leads to the production of volatile polybromomethanes.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2001.46.6.1392

Physiological constraints on bromoform (CHBr3) production by Ulva lactuca (Chlorophyta)

Emissions of CH3Cl, CH3Br and CH3I were measured biweekly for 12- to 24-month periods between March 2002 and March 2005 from monospecific stands of four dominant southern California coastal salt marsh plants. These measurements revealed large inherent differences between species and more detailed patterns of seasonal production than previously reported. Marsh plants displayed intrinsic abilities to produce methyl halides. Salt marsh plants produced 92% of CH3Cl and 90% of CH3Br emitted and only 41% of the emitted CH3I. Unvegetated areas emitted 7.9% of CH3Cl, 9.9% CH3Br, and 59% of the emitted CH3I. The accuracy of the estimated methyl halide emissions from a coastal marsh and probably other ecosystems can be dramatically improved with increasing the number of species being measured and including emission from barren (mudflats and soil) areas. Estimates of global salt marsh emissions based on vegetated and barren area are 130, 21, 5.5 (mg m-2 yr-1) for CH 3Cl, CH3Br, and CH3I, respectively, or 1.2, 3.9, and 0.8% of total global fluxes of these gases. Copyright 2006 by the American Geophysical Union.

/pdf/coastal-salt-marshes-as-global-methyl-halide-sources-from-1fer5nzacc.pdf

Steven L. Manley

Papers

Laboratory production of bromoform, methylene bromide, and methyl iodide by macroalgae and distribution in nearshore southern California waters

Phytogenesis of halomethanes: a product of selection or a metabolic accident?

Release of reactive bromine and iodine from diatoms and its possible role in halogen transfer in polar and tropical oceans

Physiological constraints on bromoform (CHBr3) production by Ulva lactuca (Chlorophyta)

Coastal salt marshes as global methyl halide sources from determinations of intrinsic production by marsh plants